CHE 6570

To provide fundamental tools which are used to
design / manage / operate a chemical plant safely

WHY TALK ABOUT SAFETY ??

• Is it all about $$ ?

• Is its importance equal to production?

• SAFETY = Loss Prevention

3

Code of Engineering Ethics
(Crowl, Table 1-1, p. 5)

• AIChE Code of Professional Ethics
• Principle # 1: Use knowledge and skill for the
enhancement of human welfare.
• Principle #2: Be honest and impartial and serve with
fidelity the public, employers and clients.
• Canon # 1: Engineers shall hold paramount the safety,
health, and welfare of the public.

4

Metrics of Safety
• How to measure safety? Important factors?
• Metrics are needed to assess the effectiveness of safety programs.
• Hazards – have potential to cause damage to people, property or
environment
• Risk – a function of likelihood & magnitude
• Understanding of risk, real & perceived, is needed for assessment of
alternatives

5

Personnel Safety
vs.
Process Safety
6
.

7
.
which results in or might reasonably have
resulted in. deaths. evacuation or
sheltering in place. significant property
or environmental damage. injuries. Process Incident Definition
A process incident is the sudden unintended
release of or exposure to a hazardous substance.

000-2.
8
. Safety Pyramid
1-2 Fatalities due to “Incidents”
10-20 Serious Injuries
100-200 Minor injuries
1.000 Near Misses
• Underlying causes of incidents at each level are often the
same. where one generally has more data.
• More serious incidents can be reduced by focusing on bottom
of pyramid.

400 .78 per day
Public: 20.200 – 113 per day
Work: 5.
.100 – 14 per day
Home: 28. Russia. mostly in China.200 – 253 per day
World wide auto deaths: estimate at over 1
million per year.000 – 55 per day
Total Deaths: 92.
India. Statistics-3
1999 US Accident Fatalities:
Motor Vehicle: 41.

by choice
•Accept the risk of smoking
•Voluntarily drive a motorcycle
•Protest a plant with a much smaller risk
14
.Voluntary or Involuntary Risk
•Concept of risk not well understood by public
•Individual choices / decisions based on
perceived risk
•Accept risk by coercion vs.

Safety in the Chemical Industry
• Risk is generally less than perceived by public. and
often out of context with readily accepted
everyday voluntary risks
• Chemical industry is held to a higher than average
safety standard
• Continuous improvement towards an accident free
workplace is necessary for credibility and the
public trust
15
.

Loss Trends in Industry
• Number and magnitude of losses increased from
1960’s through 1991
• Consistent with trend of larger & more complex
plants and processes. perhaps due to 1992 OSHA
regulations. p. Also higher pressures and
temperatures. for
1992-1996 period. 18.
• Decrease is shown in Crowl. Figure 1-9.
16
.

Key Questions
• Why do Accidents occur?
• How do Accidents occur?
• What must we do to keep
them from happening?
• When?
.

Why do Accidents Occur?
• We choose to handle dangerous process
materials and energies
– To make a living
– To provide society with desirable
products
• As long as we choose to handle them.
a potential for loss events exists
Things can be done to reduce their likelihood
and severity to negligible or tolerable levels
.

Key Questions
• Why do Accidents occur?
• How do Accidents occur?
• What must we do to keep them from
happening?
• When?
.

How Do Accidents Occur
Most follow a 3-step sequence:
•Initiation (event that starts the accident)
•Propagation (the event(s) that maintain or
expand the accident)
•Termination (the event(s) that stop the
sequence or diminish the extent)
33
.

Figure 1-7 Nature of Accidents .1
.

2
.Figure 1-8 Nature of Accidents .

Key Questions
• Why do Accidents occur?
• How do Accidents occur?
• What must we do to keep
them from happening?
• When?
.

What must we do to keep them from happening?
Management
SAFETY
Culture Technical
.

A. Kletz. Plant Design for Safety: A User-Friendly
Approach (NY: Hemisphere. 1991)
.”
T. Inherently Safer Design
“The essence of the inherently safer
approach to plant design is the
avoidance of hazards rather than
their control by added-on protective
equipment.

control is simplified. and emergency response
is eliminated. fences are
reduced in strength. Crowl’s Lion Farm
Inherently Safer Design Approach: If we are
cultivating the lions for meat. the hazard is
eliminated.
. why not use
lambs instead? This way.